1. Field of the Invention
The present invention relates to a recording medium dualizing system, and more particularly to a system for dualizing external recording medium such as a hard disk or a magneto-optical disk.
In today's information systems and apparatuses, service information and operation program have a large volume. As a result of this, providing an external recording medium and extracting information therefrom is a generally employed scheme.
Hard disks and magneto-optical disk are known as such an external auxiliary recording medium. For improved system reliability, a system operation in which the recording medium is dualized in actual operations is often employed.
2. Description of the Related Art
When determining which recording medium is to be made active in a dual recording medium system, a strict control for preventing an erroneous operation is required.
Two methods of determining an active recording medium are: 1) Maintenance personnel takes the responsibility of determining an active medium; 2) The information relating to an active system is retained internally so that the system determines an active medium in an autonomous manner.
As a means for embodying the method 1) described above, a switch for linking the system operation and the job of the maintenance personnel may be provided so as to allow the maintenance personnel to select a recording medium for the active system. However, this has drawback in that a human error leads to a change in the operating state. For example, an error may lead to an operation governed by an unwanted operation program or to a stop of the operation (recording medium malfunction).
In one approach which embodies the method 2) described above, information relating to the active system is written to a recording medium in a predetermined format, and a recording medium for the active system is determined in an autonomous manner by reading such information. This approach, however, has drawbacks in that a wait time (procedure) for reading the information stored in the recording medium is required, and there is a likelihood that the system will stop in case the active system information cannot be read due to a malfunction of the recording medium. Another problem is that, when the information relating to the active system or the information relating to the non-active system is updated, reading and writing of service information is prevented, thus leading to a reduced processing ability.
Moreover, in the method 2), when the system is stopped and restarted after an external recording medium is exchanged, or when the system is restarted following a failure in the power supply, the information stored in the main memory is not updated accordingly, or no information is stored in the main memory. Therefore, maintenance personnel have to somehow determine the external recording medium that was designated as an active recording medium.